Method of making rubber articles



Patented Feb. s, 1935 I I 1,989,717

UNITED STATES PATENT OFFICE METHOD OF MAKING RUBBER ARTICLES Andrew Szegvari, Akron, Ohio, assignor to American Anode, Inc., Akron, Ohio, a corporation of ware No Drawing. Application October 29, 1930, Serial No. 492,094

' 14 Claims. (Cl. 41-33) This invention relates to the art of rubber which the rubber is dried and vulcanized in the manufacture, and particularly to the production usual manner. The thickness of the rubber over of raised designs, lettering, etc., ofrubber. as the palm of the glove 'will be found to be quite well as rubber coatings over portions only of obuniform, but distinctly greater than that over 6 jects. Y the remainder of the glove.

It has heretofore been proposed to manufac- In an alternative process for the production of ture rubber articles or produce rubber coatings rubber coatings of variable thickness similar to by dipping a form successively in a liquid coaguthe glove described above, the form may be coated lant and in liquid latex, the film of coagulant uniformly with a solid or semi-solid coagulant 10 remaining on the form causing the coagulation film by dipping in a solution such ,as the above- 10 of the subsequently applied latex. This prementioned calcium nitrate solution, and drying. viously known process, however, has not been A second film of the same or a different coagulant adapted to the production of discontinuous coatis then applied over those portions of the surface ings, or coatings possessing a. variable thickness. where the rubber coating is to acquire a greater 16 An object ofthis invention is accordingly the thickness. When the treated form is dipped in 16 production of dipped rubber products of varying the latex, the thickness of the rubber layer coaguthicknessh Another object is the production of lated on the surface of the form is found to be rubber deposits or coatings over only the desired roughly pr p o the m u of c a ulant limited portion of the surface of a base or form. on the various portions of the form. It is thus 20 A- further object is the production of decorative possible to obtain the same results as were de- 20 designs, lettering, etc., on rubber articles. Other scribed above in a single dip in latex instead of objects will be evident from the following dein two dips. scription of the invention. In the etching of glass panes, mirrors, etc., by

This invention is practiced by providing a base sand-blasting, the portions of the glass which are or form with a film of coagulant over a portion to retain their polished surface are protected 25 only of its surface, and then bringing the coagufrom the sand-blast by some soft, resilient sublant-coated surfaces in association with a body stance. Rubber may be employed by applying a of a coagulable aqueous dispersion of rubber or coagulant to such portions of the surface, for like substance. The coagulant may be applied example by painting, or by spraying through a by brushing, spraying, by transferring from anstencil, or by printing with a rubber stamp, and 30 other surface, etc and may be associated with then immersing the glass-in latex for a few mothe aqueous dispersion by immersion therein, or ments. .The latex in contact with .the coagulant-- by flowing or spraying the dispersion over the treated surfaces iscoagulated asa firm, adherent coagulant-treated surface. coating, while the remainder of the surface is For example, a rubber acid glove is to be precovered only by an uncoagulated, liquid film 35 pared witha thickened portion on the palm and which is readily removed. The uncoagulated lathe inside of the fingers where it is exposed to tex is washed off the glass with 'water, preferably the greatest wear. The porcelain glove form is make weakly alkaline with ammonia, whereupon cleaned and a coagulant liquid such as a solution ,the glass is ready for the sand-blasting. After- 40 of one part of hydrated calcium nitrate in two wards the protective layer of rubber is readily 40 parts of acetone is brushed over the palm of the removed by rubbing, exposing the polished surform. The major part of the acetone is permitfaces again. ted toevaporate in order that the coagulant may Where an object is to be provided with a peracquire a viscosity high enough to prevent its dismanent coating of rubber over a portion only of placement by the liquid dispersion, and the form its surface, an adhesive substance is preferably 45 is then immersed in'a vulcanizable latex. After applied to that portion of its surface either before the. desired thickness of rubber has coagulated on the coagulant is applied or simultaneously therethe palm, say after 5 minutes, the form is rewith. For example, 10 parts of glacial acetic moved from the latex, completely immersed in. a acid iscautiously-stirred into a solution of 15 tank of the coagulant liquid, permitted to dry for parts of an adhesive, artificial rubber isomer in 50 1 minute, more or less, and re-immersed in the 100 parts benzol. The adhesive rubber isomers latex for 10 minutes. The form is then removed disclosed in the patent to Geer, No. 1,617,588, of from the latex and immersed for'several hours in Feb. 15, 1927, are particularly suitable. A plata tank of running hot water to leach out water- .ing rack for supporting metallic articles while soluble substances,-including the coagulant, after they are electroplated has the areas which are 55 to remain bare and conduct the current masked with paper or other suitable material, whereupon the remainder of the surface is coated with a thin layer of the above solution by spraying. The masks are removed and the rack is dipped in a vulcanizable latex until the desired thickness of rubber is coagulated. The excess uncoagulated latex is washed off the untreated portions of the rack and the deposited rubber is washed in hot running water to remove water-soluble substances, including the coagulant. The adhesive rubber isomer, however, being insoluble in water, remains between the rubber and metal as athin film which causes the rubber to adhere permanently to the metal after vulcanization.

Paper, wood, or other fibrous material is provided with a decorative coating over a portion of its surface by printing on the surface with a thick rubber cement containing approximately 5% of acetic acid. After the cement has partially dried the fibrous material is immersed in latex which is coagulated on the treated portion of the surface by contact with the acid-containing cement. The uncoaguiated latex is washed ofi the untreated surfaces, for example, by successive treatment with a solution of a of soap and ammonia, a solution containing ammonia, and then ordinary tap-water. Such decorative coatings may possess almost any desired outline from the simplest figures to the most complex, and may even include lettering, for the outlines of the coatings are very sharp and distinct.

Rubber articles may be provided with raised or embossed lettering or other designs, which may be in contrasting colors from the rubber base, by applying a coagulent to a suitable base by printing it thereon, spraying through a stencil, etc. For example, a felt pad is saturated with a solution of calcium nitrate in acetone or methanol, and a rubber stamp with a surface of the desired configuration is moistened with the coagu lant, which is transferred to a sheet of calendered paper by a printing operation. The paper is thereupon immersed in a colored latex. After a short time the paper is removed and the excess uncoagulated latex washed off as described in the preceding paragraph. The rubber letters or other designs are transferred to the rubber article, which is preferably unvulcanized, by pressing'the side of the paper which carries the rubber deposits firmly against the article and then stripping of! the paper. The rubber may then be vulcanized as usual, preferably in open steam or dry heat. It should be noted that in this process the lettering is twice transferred, once from the stamp to the paper and once from the paper to the rubber article, hence the letters in the stamp should not be reversed as in ordinary ytpe, but should be made exactly as they are to appear on the finished article. If desired, different-letters or different portions of a design may be produced in different colors and separately transferred to the rubber article in the predetermining location.

It is likewise possible to produce raised designs or lettering directly on the rubber by applying the coagulant directly thereto and immersingtherubher article itself in the latex. However, it will generally be found that it is more convenient, and that better results are secured, when the rubber istransferred from another surface as described above, particularly when the design or lettering is to be applied to a small portion only of the rubber .articles. The lettering may even be produced on a sheet of unvulcanized rubber ing the coagulated rubber.

which is then cut out in the-form of a medallion or manufacturer's label and afiixed to the rubber article as a complete unit. This process is also applicable to the transfer of rubber letters to the surfaces of other substances such as metal, wood, paper, etc., an adhesive being preferably employed in this modification.

In the examples given above certain specific coagulants have been described, but it is to be understood that other coagulants may be substituted therefor. For example, salts of polyvalent metals, such as magnesium chloride, calcium chloride, calcium nitrate, calcium lactate, zinc chloride, aluminum chloride, etc., may be employed, either alone or together with a free acid, in solutionin water or an organic solvent such as alcohol, ether, acetone, an ester, etc. The coagulant may consist of a free acid such as formic, acetic, citric, lactic, hydrochloride, etc., in an appropriate solvent or diluent. The coagulant may contain colloids, high-boiling solvents, wetting agents, etc., to modify its properties for particular uses.

The aqueous dispersion may be any natural or artificial dispersion of rubber or a like substance, including natural latices of caoutchouc and gutta-percha, artificial dispersions of crude rubber, synthetic rubber,reclaimed rubber, rubber isomers, etc. The dispersion may be concentrated, or vulcanized, or otherwise treated before it is used, and may contain pigments, softeners, vulcanizing agents, or other additions.

It is therefore to be understood that this invention is not limited to the examples enumerated above, which are merely illustrative of certain manners of carrying out my invention, but that numerous modifications may be introduced without exceeding the spirit and scope of the invention as defined in the appended claims.

I claim:

1. The method which comprises applying to the surface of a base a film of coagulant whose thickness varies over the said surface, and thereafter applying a coagulable dispersion of rubber.

2. The method which comprises applying a coagulant to a portion only of the surface of a' base, in a predetermined design, and thereafter applying a coagulable dispersion of rubber.

3. The method which comprises applying a coagulant to the surface of a base in a predetermined design, and thereafter dipping the base in an aqueous dispersion of rubber.

4. The method which comprises coating a portion only of the surface of a base with a coagulant solution in a predetermined design, placing the base in contact with a body of an aqueous dispersion of rubber, and drying the coagulated rubber.

5. The method which comprises app yin a film of a solution of a coagulant in a volatile solvent to a base in a predetermined design, permitting the major portion of the solvent to evaporate, and dipping the base in an aqueous dispermined design, immersing the base in an aqueous dispersion of rubber, and drying and vulcaniz- 8. The method which comprises coagulating the rubber from an aqueous dispersion of rubber locally on a. base member in a predetermined configuration, and transferring the coagulated rubber deposits from the surface of the base figuration, and transferring the coagulated rubber deposits from the surface of the base member to the surface of a flexible sheet material by contact therewith.

10. The method which comprises coagulating the rubber from an aqueous dispersion of rubber locally on a base member in a predetermined design, and transferring the coagulated rubber deposits to a rubber surface by contact therewith.

11. The method which comprises applying a coagulant to a base in a predetermined design, immersing the base in an aqueous dispersion of rubber, and transferring the deposited rubber to a continuous rubber surface by pressing the base with the rubber deposits thereon against the rubber surface and removing the base.

12. The method which comprises applying a fllm of a liquid coagulant to the surface of a base member in a predetermined design, immersing the base member in an aqueous dispersion of rubber, transferring the deposited coagulated rubber to an unvulcanized rubber surface by contact therewith, and vulcanizing the rubber.

13. The method which comprises applying a film of a solution of a coagulant in a volatile solvent to the surface of a base member in a predetermined design, permitting a major part of the solvent to evaporate, immersing the base member in an aqueous dispersion of rubber, transferring the deposited coagulated rubber to an unvulcanized rubber surface by contact therewith, and vulcanizing the rubber.

14. The method which comprises applying a coagulant to a figured surface, transferring the coagulant from the figured surface to the surface of a base member by a printing operation, immersing the base member in a latex composition of one color, transferring the deposited coagulated rubber to an unvulcanized rubber composition of another color by contact therewith, and vulcanizing the rubber.

ANDREW SZEGVARI. 

